The extraction process has been used for centuries for the isolation of desirable materials, primarily from plant matter. The process involves the mixing of a solvent with extractable material, separation of the solution that is formed, and removal of the solvent from the solute, a desired material.
U.S. Pat. No. 9,242,189 to Buese et al. disclosed a continuous extraction unit that employs two or more removable and replaceable extraction chambers to allow retention of the extraction solvent in the unit without requiring stoppage of flow and can allow extract removal with a nearly constant rate when a multiplicity of extraction chambers are employed. The unit employs a heat exchanger that is a combined condenser and an expansion chamber where an expansion valve promotes vaporization and separation of a liquid solute extract and gaseous solvent in a single unit.
A method where extraction chamber that allows liquid transfer of a solvent from an extraction chamber that has depleted extractable material to another extraction chamber containing fresh extractable material absent the solvent can be carried out in a rapid or continuous manner is desirable. A method of extracting using these extraction chambers to allow establishment of a partitioning of extract from the extractable material to a solvent to equilibrium within a freshly charged extraction chamber can occur over a period of time that minimizes the time in which the extraction chambers must reside in the flow of the continuous extraction unit to extract and remove all extract is desirable. A double phase change heat exchanger, where condensation of a gas to liquid occurs in one portion of the heat exchanger and evaporation of a liquid to gas with a liquid-gas separation of extract from a solvent occurs rapidly is desirable.